Prediction Of Spark Ignition Engine Testing Engineering Essay

Prediction Of Spark Ignition Engine Testing Engineering Essay Introduction Internal combustion engines date back to the 1800s. Since then, they have improved considerably as the knowledge of the engine process has evolved. The engine process is seen as a complex one and so, calculating the various engine parameters is a complicated task. There have been a number of computer programmes with the aim of estimating these parameters; OpenWAM is relatively new simulation software that intends to do this. OpenWAM, or open wave action model, is a free, open-source code that has been developed to solve the thermo- and fluid dynamics of compressible flow through the different components of an engine. The aim of this project to use OpenWAM to generate a full set of engine performance and fuel economy prediction estimates and to then compare these with experimental results. The engine in question is that of a BMW-Mini Direct Injection Spark Ignition Engine. It will be tested over a range of different operating loads and speeds. A successful interpretation of this softw are, and the results, could optimise the operation of the internal combustion engine. This Interim Report details a synopsis of the literary review done to date. It includes the main principles of an internal combustion engine, including the intake and exhaust system as well as the in-cylinder process. The details of OpenWam software are mentioned and its applications. The aims of this project are also described. Literary Review Basic Principles Internal combustion engines have one main purpose, that is; the production of mechanical energy from the chemical energy contained in the fuel. The basic principles behind any reciprocating engine are the same. The cycle has four stages; intake, compression, expansion, exhaust. The intake stroke begins with the piston at the top of the cylinder (TDC) and the inlet valve open. As the piston moves down a vacuum is created and air-fuel mixture is drawn into the cylinder. When the piston reaches the bottom (BDC) the inlet valve is closed and the compression stroke begins. This involves the piston moving up and compressing the air-fuel mixture. This is then ignited in the expansion stroke. As the air-fuel mixture is heated it expands, pushing the piston down, to bottom centre (BC). The outlet valve is then opened and the exhaust gases are removed to the atmosphere. The piston moves up to TDC as the exhaust stroke finishes the cycle [1]. Figur-1 Basic Combustion Cycle The engine used in this project is a four-cylinder engine. Most engines used for automobiles have four cylinders. The number of cylinders is an important consideration for the overall performance of an engine. Each of the cylinders, contain a piston that is connected to the crankshaft. The movement of the piston rotates the crankshaft. The crankshaft is what turns the wheels. The more pistons powering the crankshaft means more power can be generated in less time. The engine used in this project is a Direct Injection Spark Ignition Engine. This means that the fuel is injected directly into the cylinder. With regular engines, the fuel and air is mixed before entering the cylinder. This will be discussed in further detail in preceding sections. Basic Components https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjRGp6-t_AoyFqKyh_y_CsmlsJvoMMLQqKc7IELHJu7sROE9sJhy5dVF4Sb4IP8LrkvduVQ7qCRAV9-U3dIGNn_8FXi54CDqtMoXj1PBm-Xz-h3zmn8_Jlj-a_sCxh7iUbQLdp_4ldHDtE/s1600/BMW_S1000RR_ENGINE_CUTAWAY_700x462_700.jpg Figure-2 Engine Cutaway Intake The engine intake process governs many important aspects of the flow within the cylinder. The efficiency of combustion and the production of pollutants are strongly dependent on the flow of air during the intake stroke. Fluid Flow during Intake Process The gas flowing into the cylinder, through the intake valve, behaves as a conical jet. The axial and radial velocity components, of the jet, are up to ten times that of mean piston speed. High speeds of the fluid lead to turbulence. Turbulence is generated due to the large velocity gradient formed when the jet separates from the valve. Turbulent flow undergoes irregular mixing and the speed of the fluid is constantly changing magnitude and direction. By increasing the rate of momentum, heat and mass transfer of the fluid, turbulent flow encourages mixing within the cylinder. It leads to the formation of vortices. Vortices are large-scale rotating flow patterns that are unsteady and react with each other. These vortices are important governing factors of the overall behaviour of the flow. They remain until the end of the intake stroke, where they become unstable and break up. Turbulence is essential to the effective operation of an SI engine. It is a goal of any engine to maximise the turbulent effect, however this is complicated by the fact that flow patterns change during the engine cycle. They are largely dependent on the design of the intake system and are quite sensitive to small variations in flow. They are largely dependent on the design of the intake system and are quite sensitive to small variations in flow. This can lead to substantial cycle-to-cycle variations. The turbulent flow of air within the combustion chamber is almost exclusively generated during the intake stroke [3] Volumetric Efficiency Pg.209 Volumetric efficiency is defined is the measure of success with which air is inducted into an engine. It is defined as the ratio of the volume flow rate of air into the intake system, to the rate at which the volume is displaced by the engine. More simply, it is the actual rate at which air enters the cylinder, over a given period in time, to the theoretical rate at which it should enter, over the same time period [6]. C:Documents and SettingsucdMy DocumentsDownloadsCodeCogsEqn.gif Where; ÃŽÂ ·v volumetric efficiency Ma mass flow rate of air ÃŽÂ ¡a, 0 density of air Vd displaced cylinder volume N crankshaft rotational speed Volumetric efficiency is used to measure the overall effectiveness of an engine. It is mainly affected by the density of air entering the cylinder, the design of the intake and exhaust manifolds, and the timing of the intake and exhaust valves. The high temperatures within the combustion chamber have a limiting effect on the mass flow rate of air into the system, thus reducing volumetric efficiency. To counteract this, air with higher density, i.e. lower temperature and higher pressure, is preferred. This increases the amount of air entering the system, improving the volumetric efficiency. The intake and exhaust manifold and valve timing have similar limiting effects. The amount of air entering the cylinder is also largely dependent on these parameters. These parameters constrain the maximum possible engine power. This is why the volumetric efficiency of an engine is very important. Frictional Losses Pg.212 Losses due to friction have a major impact on the engines performance. During the intake stroke, losses due to friction, in every part of the intake system, mean the in-cylinder pressure (pc) is less than the atmospheric pressure (patm). The difference between these two values is dependent on the square of the speed. The total friction loss is the combined losses from each of the components in the intake system; air-filter, inlet manifold, inlet valve and inlet port. Each component adds a loss of a few percent, on average, pc can be 10-20% lower than atmospheric [1]. RAM effect During the intake process the RAM effect needs to be considered when calculating an engines performance. It occurs when the open valve phase is extended beyond that of the intake stroke to improve charging the cylinder and make best use of the inertia of the gases in the intake system. As the piston reaches TDC during the intake stroke, the inlet valve does not close immediately. Instead it remains open, as the compression stroke begins. This allows any extra air to be added to the cylinder. The momentum of the air during the intake stroke carries it into the cylinder even after the piston has reached the bottom of the cylinder. At high speeds, the intake valve can remain open for longer to optimize the RAM effect. The inlet valve isnt closed until a crank angle of approximately 40-60o after BDC to take advantage of this. However for engines running at lower speeds, the momentum is not high enough, this can cause the air already in the cylinder to be forced out. Adapting the inlet va lve open phase can have a major impact on the engines performance [2]. Overlap When considering both the RAM effect and the blowdown phase (discussed later), it is clear to see that there is a period of overlap, when both the inlet and outlet valves are open. If the pressure inlet to outlet ratio is less than one then backflow occurs. This involves a rush of exhaust gases out through the exhaust manifold that aids the intake of air into the cylinder during the intake stroke. This works best at higher speeds, when its main advantage of overlap is the improvement in volumetric efficiency. As with any fluid flowing through a system of intricate pipes, cylinders, valves, there are friction, pressure and inertial forces present. The importance of these forces is dependent on the both the velocity of the fluid and the geometry of the system. These forces along with the effects of changing engine design affect the volumetric efficiency. In-cylinder (NB Pg.372,) Gas motion within the engine cylinder is one of the major factors that control the combustion process. Both the bulk motion of the gas and the turbulence characteristics of the fluid are important. The in-cylinder combustion process can be divided into four distinct phases; Spark-Ignition Early Flame Development Flame Propogation Flame termination Spark Ignition Pg 585 Close to the end of the compression stroke, the discharge between the spark plug electrodes by the ignition system starts the combustion process. The spark develops a self-sustainable and propagating flame. The function of the ignition system is to initiate the flame propagation process, to repeat this for each cycle, over the full range of load and speed of the engine, at the appropriate time. Spark-timing is an important consideration during the engine process. It can have a number of affects on the efficiency, formation of pollutants and other parameters of the engine. Advancing the timing, so that combustion occurs earlier in the cycle, increases the peak cylinder pressure (compression stroke work transfer, which is work form piston to gases in the cylinder, also increases). This is because more fuel is burned before TDC and the peak pressure moves closer to TDC where the cylinder volume is smaller. Delaying the timing means the peak pressure occurs later in the cycle and is also decreased in magnitude. This is because more of the fuel is burnt after TDC. Higher peak cylinder pressure result in higher peak burned gas temperatures, and therefore higher NOx formation results. Maximum Brake Torque (MBT) is the use of optimal ignition timing to take advantage of internal combustion engines max power and efficiency. It occurs when the compression stroke work transfer (which is from the piston to the cylinder gases) is increased and the expansion stroke (which is from cylinder gases to the piston) is reduced. The MBT timing occurs when the magnitude of these two opposing trends just offset each other. Altering the timing from MBT lowers the torque [4]. Generally, spark timing is delayed so as to avoid abnormal combustion. Abnormal combustion refers to either knock or surface ignition. Knock is the name given to the noise transmitted through an engine when a spontaneous ignition of a portion of the end-gas occurs. End-gas is the mixture of fuel, air and residual gas ahead of the propagating flames. The spark plug ignites one flame front, however an uncontrolled combustion then occurs and an extremely rapid release of most of the chemical energy in the end-gas leads to the initiation of multiple flame fronts. When these multiple flame fronts collide, the cylinder pressure increases and causes the piston, connecting rods and bearings to resonate [5]. Knock has a direct impact on efficiency because it limits the maximum compression ratio that can be used in any cylinder. Surface-ignition is another type of abnormal combustion. It occurs when ignition is initiated by a local hot-spot located on the walls of the cylinder. Direct Injection Spark Ignition Direct Injection (DI) engines deliver the fuel directly into the combustion chamber. The traditional method pre-mixes air and fuel in the intake manifold and then delivers it to the cylinder. However with DI engines, air enters through the intake manifold, where a specific amount of fuel is sprayed into the cylinder. Early Flame Development Pg.846-850 During the in-cylinder process of compression and combustion, the increasing cylinder pressure forces some of the gas in the cylinder into the corners or narrow volumes connected to the combustion chamber, e.g. the volumes between the piston, rings and cylinder wall. Most of this gas remains unburned in the primary combustion process as the flame cannot enter these narrow regions. Spark-Timing Pg 585 There is always an optimal spark timing for all operating conditions of an engine. MBT is most ideal at WOT however is not desired when the engine is at idle. Although MBT is desired at WOT it is wise to retard timing slightly to prevent knock that may occur and to create a small safety margin. It is possible to calculate the MBT of an engine by taking into account of all the operating conditions of an engine through its sensors. Operating conditions are defined by the engine parameters lambda, engine load, internal exhaust gas recirculation, engine speed, and of course spark advance. Magnusson, J. 2007 An Investigation of Maximum Brake Torque Timing based on Ionization Current Feedback Exhaust ( Pg. 626,570,) The level of sulfate emissions depends on the fuel sulfur content. Unleaded gasoline contains 150 to 600 ppm by weight sulfur, which is then oxidized during the combustion process to form SOx. The emission of particles is increased when the engine is cold, i.e. following start-up. The exhaust temperature has a significant effect on pollutant formation. Particles form in the exhaust manifold and either are emitted immediately or deposit on the walls of the exhaust. Many of these are removed when the engine is suddenly accelerated. The exhaust geometry, specifically the diameter, determines the amount of particles emitted. Incomplete combustion due to bulk quenching of the flame in that fraction of the engine cycle where combustion is relatively slow, is a source of hydrocarbons in engines. Such conditions are most likely to occur during transient engine operation when the air/fuel ratio, spark timing, and the fraction of the exhaust recycled for emission control may not be properly matched. Engine Design The major combustion chamber design objectives which relate to engine performance and emissions are; Pg. 845-> A fast combustion process, with low cycle-by-cycle variability, over the full operating engine range A high volumetric efficiency at wide open throttle Minimum heat loss to the combustion chamber walls A low fuel octane requirement Faster burn process is more robust and results in the engine being able to operate satisfactorily with much more EGR, or much leaner, without a deterioration in combustion quality. Faster burning chamber designs exhibit much less cycle variation, this permits better control of NOx within the engine. This is achieved in a number of ways. Swirl is used to speed up the combustion process in some spark-ignition engines. Swirl is defined as the organized rotation of the charge about the cylinder axis. Swirl is created by designing the intake system such that the flow enters the cylinder with an initial angular momentum. This is done in two ways, either the flow is discharged into the cylinder tangentially towards the cylinder wall. or intake? High volumetric efficiency is required to obtain the highest possible power density. Effective vvalve open area, which depends on valve diameter and lift, directly affects volumetic efficiency. Swirl speeds up process and achieves greater combustion stability. Heat transfer to chamber walls has a major impact on efficiency. Blowdown amount of time/distance/degrees between exhaust port opening and the transfer port opening Muller. P, 2009, Muller Machine, http://www.muller.net/mullermachine/index.html The blowdown process is similar to that of the RAM effect. It is necessary to open the exhaust valve before the piston reaches the bottom of the stroke, as this allows any excess pressure, pressure left over from the last cycle, to be released from cylinder. This ensures there will be no pressure acting against the piston on the compression stroke. Accurate exhaust valve timing is essential. At higher speeds, the valve will have to be opened sooner, whereas for lower speeds if the valve is opened to soon means pressure is lowered and losses are incurred. AutoWare, 1998, Valve Timing Performance  , http://www.auto-ware.com/combust_bytes/valvetiming.html The exhaust manifold operates at pressures significantly above atmospheric. Pollutants (pg.626, 570, CO-Pg. 593, summary Pg.618,) Theoretically, the combustion process of hydrocarbon fuels, such as petrol, completely oxidizes the fuel and the only by-products are carbon dioxide and water. However, under actual conditions this is rarely, if ever the case. The products of combustion from an internal combustion engine produce pollutants. This is due to the varied composition of the fuel for each cycle. Impurities in the fuel itself mean complete combustion is not possible. Poor control of the air-fuel ratio and variations in the combustions temperature also contribute to the formation of pollutants. The main pollutants formed are sulfur oxides (SOx), nitride oxides (NOx), carbon monoxide (CO) and particulate matter (PM). These pollutants have detrimental health effects. The presence of a catalytic convertor reduces the amount of harmful emissions entering the atmosphere by changing the composition of the pollutants. One of the most important variables in determining spark-ignition engine emissions is the fuel/air equivalence ration. GRAPH OF EMISSIONS!! To ensure smooth and reliable operation, SI engines are typically run close to stoichiometric, or slightly fuel-rich. From graph (ABOVE), lean mixtures give lower emissions until the quality becomes poor and back-fire occurs. In a cold engine, fuel vaporization is slow, the fuel flow is increased to provide an easily combustible fuel-rich mixture in the cylinder. Until the engine warms up and the enrichment is removed, the CO and HC emissions are high OpenWAM Simulation Software OpenWAM is a 1-dimensional gas-dynamics engine thermodynamic cycle simulation code. It was developed by the CMT- Motores Tà ©rmicos of the Universidad Polità ©cnica de Valencia, Spain. openWAM Modeling is an important technique for the optimization of internal combustion engines (ICE). The use of calculation models together with experimental tests is producing unquestionable successes due to the fact that both techniques complement each other. 1D wave action models simplify the engine by means of ducts, where only one dimension is considered, and volumes where mass accumulation is considered and the gas properties are uniform in the entire element. Finally, non dimensional models are used to solve connections between 1D and 0D elements. Thanks to more than 20 years, more than 10 PhD Thesis and many research projects and publications, CMT-Motores Tà ©rmicos has developed an own 1D gas dynamic tool called WAM which gathers an important know-how on air management, compressible flow, turbocharging, chemical species tracking, numerical analysis and many other aspects of engine modeling http://www.cmt.upv.es/WAM_02_02.aspx 1 dimensional modeling can reproduce the behavior of the engine under transient conditions when the injected fuel and the engine speed change during the simulation. For these applications, a heat transfer model is very important to take into account the heating process that the different parts of the engine undergoes during the transient. http://www.cmt.upv.es/img/WWam04.png http://giantmaw.com/Photo%20Album/Image%20Library/Cars/BMW/MWerks%20Forums%20the%20BMW%20Engine%20FAQ_files/4981_832.jpg

The Influence of Stress on Dopamine Levels :: Biology Essays Research Papers

The Influence of Stress on Dopamine Levels In the quest to survive, every living organism is equipped with the armor to withstand the impacts of stress. The African savanna leaves the zebra in an anxiety-ridden position of vulnerability to predators. Stress may can be as basic as the lack of food, habitat, or reproductive success. Humans are especially aware of the impacts of stress due to the nature of todayà ¢s contemporary lifestyle. Too many daily demands can give a person anything from insomnia to indigestion to depression. Every person is equipped to naturally deal with large amounts of stress, but when these amounts exceed what the body can handle, discomfort is considerable. Besides the qualitative approach to coping with stress, what bodily mechanisms are responsible for dealing with anxiety? The nervous system is almost solely credited with this task. The complex interaction system between billions of individual neurons facilitates large number of behaviors that result due to inputs originating inside and outside the organism. Spaces between neighboring neurons are called synapses, and one way in which they communicate is by sending chemical signals called neurotransmitters across the presynaptic membrane to the postsynaptic membrane. Years of nervous system research have determined that stress activates the neurotransmitter, dopamine. The functions of dopamine are numerous, but in general it inhibits transmission of nerve impulses. This transmitter is found throughout the body, though mainly housed in the brainà ¢s interior basil ganglia, in the frontal lobe of the information-processing center of the brain, or in the limbic system (1). Many chronic diseases result from the overproduction or underproduction of dopamine. The dopamineà ¢s inability to move into the frontal lobe of the brain results in the inability to control fine motor movement and is familiarly called Parkinson Disease(1) . If the flow of dopamine throughout the nervous system is not allowed to circulate as usual, then schizophrenia follows (1). Now that the extreme abnormalities of dopamine have been discussed, letà ¢s look at how dopamine affects the average person who is subjected to a stressful environment. One study maintains that the chewing behavior of mice is a response to stress, and therefore it serves as a coping device. The body responds to stress by the activation of the cerebral dopaminergic (DA) system. The study shows that when given the option of chewing, the activation of mouse DA system is drawn out (2) In other words, when allowed to chew, a mouseà ¢s body will have prolonged the presence of stress-managers; this coping mechanism reduces the impact of the stress.

Planning and Enabling Learning Essay

In this assignment I am going to explain my approach to the research I have carried out and summarise my findings. To plan and enable learning, as a trainer I must ensure that my training is student centred and inclusive to all. There are many theories and suggestions to consider how this should be done in an adult learning environment. In order to enhance my current knowledge I decided to use reference books, publications, journals and websites to research relevant topics. I also utilised my mentor as a sounding board for ideas and a point of discussion for areas I was unsure about. I reflected on my existing knowledge and my research for Unit One – Preparing to Teach in the Lifelong Learning Sector. I wanted to access new models and theories and link these into the context of my own teaching practice. To do this I searched the internet for reviews of reference material for planning and enabling learning, which I then purchased. I found that my research could be extensive. I had to remain focused and choose topics to explore that I found interesting and relevant to my learning environment and style of delivery. Adult learners need to take responsibility for their own learning. If learners are active in setting their own targets and understand what they need to achieve, motivation and self esteem will reassure their learning experience. Understanding methods of negotiation and inclusivity provides learners with the most appropriate experience, engages the whole group and builds a good rapport. This can be gleaned from the identification of needs as per Ecclestone (1996). I focused my research on the impact of initial assessment on the learning journey. From my experience initial assessment results are not used effectively and the process of initial assessment is usually carried out purely to comply with procedure. My experiences are confirmed by The Chief Inspector’s Report (2003). The Adult Learning Inspectorate found that ‘many providers are using a screening test but not following this up†¦. the results of the assessment are not being used to inform the ILP’ (Wilson, L, 2008, p.139). Initial assessment can have a huge impact on delivery of learning and can form the learner’s ideas, goals and highlight areas of support required. Scales (2008, p.178) states that initial assessment ‘should be handled sensitively to welcome learners in rather than scare with formal testing and assessment procedures’. I agree with this, however, the nature of the assessment will depend on the level and content of the course commenced. Some programmes require a robust assessment process to set parameters and determine suitability to join the course. Wallace (2007, p.154) describes the three key components that come together at the beginning of a programme – the teacher, the learners and the syllabus or specifications of the course. This makes complete sense. To deliver an effective programme and meet the learning outcomes the key elements must come together and crystallise. This will then inform the delivery of the overall programme. This led me to further explore my research around inclusive learning. I chose to continue down the route of motivation and the impact this has on learners. Petty (2009, p.55) noted that ‘Maslow showed that there is only one way of motivating your students. And that is to ensure that your students’ belongingness, esteem and self-actualisation needs are nourished through the learning activities you devise’. Using information from the initial assessment, such as learning needs or styles, resources need to be created and adapted to ensure learning is effective and relevant. Functional skills should be tested and developed when appropriate. In my research I focused on the practicalities of embedding these skills and reports published relating to post 16 education. In the training I deliver I can embed a variety of functional skills to allow individuals to maintain these skills and develop them further. Wilson (2008) suggested that incorporating ICT into teaching doesn’t always suit the teacher and/or learner. This can be the case with the types of sessions I deliver. Functional skills should naturally develop from a session; they can’t be forced into a session if they are inappropriate. Communication is the thread throughout a learning experience that encourages learning and development between the trainer and the learner. It is my responsibility to recognise potential barriers and utilise strategies to overcome these. This is the route I took with my research. I came across theories such as the Communication Climate (Adler et al, 1998) and Emotional Intelligence (Goleman, 1995). Again, I found a real link to negotiating with and including learners. Goleman (1995) believed that ‘if emotions and feelings are not recognised and managed by teachers and learners, then effective learning cannot occur’. My research has broadened my knowledge and understanding to take forward into the classroom. The brief I have provided only really scratches the surface from the extensive reading I carried out; however I will have the opportunity to explore these further within this unit.

BUSINESS RESEARCH PAPER

BUSINESS RESEARCH PAPER Business Research Paper assignment is considered to be one of the most important papers to be written. Good business research paper not only covers major business aspects, but also includes such subjects like marketing, economics, advertising promotions, successful sales, HR management, etc. And, yes, as you start writing your business paper you should have knowledge of all these topics that must be included in your perfect business research paper or other essay writing. If find yourself that you do not possess enough subject matter information, then buckle up to get this knowledge online or library books. Prepare in advance, start writing your paper as soon as possible at least in your mind. Sometimes you may find yourself that you don’t have enough real-time experience or knowledge of business. Then you should consult others and talk to business related people in order to get more information that will be perfect for your business research paper. As a help, recall your previous corporate work experience and analyze existing business patterns. It would be great if your will include real-life experiences and examples that will make your business research paper complete and profound. In case you are ready to accept help from essay writing service, we will be able to offer you great price and quality. You will receive you’re A-grade research paper on time as agreed. We know that we offer great deal. Our friendly customer support service will have contact with your 24/7. Dealing with our company is convenient and easy. We strive to make your academic study experience to be positive. In order to receive your best business research paper, we will need very detailed and clear instructions from you. You will be able to keep regular contact with your professional writer who will be working at your business research paper. The earlier you place your order, the better price you will get. Business Plan Essay Majority of business companies have different requirements that‘s they need a clear business plan. The process of writing a good business plan needs to state clearly business goals. It should have a market overview and information about existing and present competitors. We have gathered a team of professionals who are able to write successful project that will include marketing, sales part, financial part, hr management part, etc. The most important part of any business oriented writing is creating a genuine statement. This business statement will provide a clear vision of what the business stands for and wants for development. We are ready to create for you a special declaration that clearly states the vision of your business.   All you have to do is to contact our customer service and order online a business research paper or other custom essay papers. A true business plan or business research paper will have a clear business structure of the particular company or business. It will possess the companys business strategy and rational mind analysis.

Indus Civilization Timeline and Description

Indus Civilization Timeline and Description The Indus civilization (also known as the Harappan Civilization, the Indus-Sarasvati or Hakra Civilization and sometimes the Indus Valley Civilization) is one of the oldest societies we know of, including over 2600 known archaeological sites located along the Indus and Sarasvati rivers in Pakistan and India, an area of some 1.6 million square kilometers. The largest known Harappan site is Ganweriwala, located on the bank of the Sarasvati river. Timeline of the Indus Civilization Important sites are listed after each phase. Chalcolithic cultures 4300-3200 BCEarly Harappan 3500-2700 BC (Mohenjo-Daro, Mehrgarh, Jodhpura, Padri)Early Harappan/Mature Harappan Transition 2800-2700 BC (Kumal, Nausharo, Kot Diji, Nari)Mature Harappan 2700-1900 BC (Harappa, Mohenjo-Daro, Shortgua, Lothal, Nari)Late Harappan 1900-1500 BC (Lothal, Bet Dwarka) The earliest settlements of the Harappans were in Baluchistan, Pakistan, beginning about 3500 BC. These sites are an independent outgrowth of Chalcolithic cultures in place in south Asia between 3800-3500 BC. Early Harappan sites built mud brick houses, and carried on long-distance trade.The Mature Harappan sites are located along the Indus and Sarasvati rivers and their tributaries. They lived in planned communities of houses built of mud brick, burnt brick, and chiseled stone. Citadels were built at sites such as Harappa, Mohenjo-Daro, Dholavira and Ropar, with carved stone gateways and fortification walls. Around the citadels were an extensive range of water reservoirs. Trade with Mesopotamia, Egypt and the Persian gulf is in evidence between 2700-1900 BC. Indus Lifestyles Mature Harappan society had three classes, including a religious elite, a trading class class and the poor workers. Art of the Harappan includes bronze figures of men, women, animals, birds and toys cast with the lost was method. Terracotta figurines are rarer, but are known from some sites, as is shell, bone, semiprecious and clay jewelry.Seals carved from steatite squares contain the earliest forms of writing. Almost 6000 inscriptions have been found to date, although they have yet to be deciphered. Scholars are divided about whether the language is likely a form of Proto-Dravidian, Proto-Brahmi or Sanskrit. Early burials were primarily extended with grave goods; later burials were varied. Subsistence and Industry The earliest pottery made in the Harappan region was built beginning about 6000 BC, and included storage jars, perforated cylindrical towers and footed dishes. The copper/bronze industry flourished at sites such as Harappa and Lothal, and copper casting and hammering were used. Shell and bead making industry was very important, particularly at sites such as Chanhu-daro where mass production of beads and seals is in evidence.The Harappan people grew wheat, barley, rice, ragi, jowar, and cotton, and raised cattle, buffalo, sheep, goats and chickens. Camels, elephants, horses, and asses were used as transport. Late Harappan The Harappan civilization ended between about 2000 and 1900 BC, resulting from a combination of environmental factors such as flooding and climatic changes, tectonic activity, and the decline of trade with western societies.   Indus Civilization Research Archaeologists associated with the Indus Valley Civilizations include R.D. Banerji, John Marshall, N. Dikshit, Daya Ram Sahni, Madho Sarup Vats, Mortimer Wheeler. More recent work has been conducted by B.B. Lal, S.R. Rao, M.K. Dhavalikar, G.L. Possehl, J. F. Jarrige, Jonathon Mark Kenoyer, and Deo Prakash Sharma, among many others at the National Museum in New Delhi. Important Harappan Sites Ganweriwala, Rakhigarhi, Dhalewan, Mohenjo-Daro, Dholavira, Harappa, Nausharo, Kot Diji, and Mehrgarh, Padri. Sources An excellent source for detailed information of the Indus civilization and with lots of photographs is Harappa.com. For information on the Indus Script and Sanskrit, see Ancient Writing of India and Asia. Archaeological sites (both on About.com and elsewhere are compiled in Archaeological Sites of the Indus Civilization. A brief Bibliography of the Indus Civilization has also been compiled.

The Methods of Selection in the Recruitment Process Assignment

The Methods of Selection in the Recruitment Process - Assignment Example If the organization does not come to terms with these methods of selection, it hires other companies which search for the required talent. However, what is needed here is an understanding that shall reach upon the premise of hiring people who are skilled enough to deliver the goods as and when required. Recruitment process is important to understand within an organization because it is the basis of resource provision that employers look forward to having (Bierman, 2002). The recruitment process paves the way for the growth and development domains of an organization since it finds the ways and means through which success will be deciphered in a proper way. What is even more significant is the way under which the human resources management department deals with the process of recruitment that shall only make the entire process understandable to the publics who are outside the domains of the organization (Noe, 2009). These publics would want to know what kind of recruitment strategies a re in place within the organization and where the hiring regimes are coming into full action. Since these publics have a fair amount of say within the working methodologies, it is only natural to think of the discussion of stakeholders because these stakeholders have one or the other stake within the organization. Either the shares are being looked after by these stakeholders or they have invested a fair bit under the aegis of the organization (Laser, 1994). The need is to realize where the stakeholders deem the company in a positive way and what kind of optimism they have in mind regarding the chosen organization. In the same light, the organizational discourse must find a way through which the recruitment processes are handled in an ethical and moral way. If the hiring and firing domains are settled properly by the selection methodologies which are in place, then this should mean that the organization is doing something right for the new hires. This would be translated in the form of people joining its fore and aspiring to become a part of it in the coming times as well (Mckinney, 1991). However, many organizations are not well equipped to tackle all these issues and end up being at the receiving end of the public wrath for a number of reasons. The recruitment processes within China and the United Kingdom are important to understand because it outlines the basis of properly utilizing the resources within the domains of an organization. If the recruitment process manifests time delays and similar issues, then it would mean that there are serious problems that exist within the fore of hiring individuals within an organizational setting. Therefore the role of the human resources management department

Learning Styles Essay Example | Topics and Well Written Essays - 250 words

Learning Styles - Essay Example I think that everyone should know the way they learn. However, if an individual does not know how they learn they may find it a struggle to learn. They may be trying to learn the wrong way they may make them become frustrated and give up. When I was in high school I was not a good student. I received c’s and d’s. I was trying but l did not have anyone to show me how to learn so I gave up. It was not until I went to collage that I learned how to learn. Now I love to learn and I try to learn from different sources (LeFever, 2003). In taking the learning inventory I have found that there are few techniques that I have not tried; such as using graphics, tables, and spreadsheets to organize material, walk back and forth, and reading out loud. I would also like to try using things in my home and on the street to memory things. Throughout, my collage learning experiment I have learned not to give up. If I cannot learn in one way there are always ten other ways to try to learn the material (LeFever,